"Shooting 30 on the front side was obviously big momentum and got my confidence going," the 34-year-old told reporters after celebrating his breakthrough on the U.S. circuit. "I tried not to get too conservative.
"I tried to keep playing, tried to make birdies where I had a chance and tried to stay in the moment. And I was able to pull it off today. It feels great."
Fellow American JJ Henry, helped by an eagle at the par-five 12th, fired a sparkling 63 to secure second place while Cejka had to settle for a five-way tie for third at 15-under after closing with a 72.
"On this golf course, you miss three shots in two holes it's really difficult to bounce back," Cejka said after surrendering the lead by stumbling to the turn in two-over 38.
"Bill played really well today so I knew to win I needed to shoot two or three-under at least," said Cejka, who was also bidding for his first PGA Tour victory. "I gave it the best I could, and I gotta wait for another week."
Most of the PGA Tour's biggest names were competing this week in the WGC-Bridgestone Invitational at Firestone Country Club in Akron, Ohio.
(Writing by Mark Lamport-Stokes in Akron, Ohio; Editing by Frank Pingue/Ian Ransom)